fune/browser/components/newtab/content-src/asrouter/docs/telemetry.md

Messaging System & Onboarding Telemetry

For historical reasons, the current (but soon-to-be legacy) Messaging System & Onboarding telemetry documentation is mixed in with the Activity Stream documentation. All except the main documentation is at metrics we collect and the data dictionary.

Migration to Glean

Code all over the messaging system passes JSON ping objects up to a few central spots. It may be annotated with attribution along the way, and/or adjusted by some policy routines before it's sent. A version of the JSON that's been transformed slightly further is sent to Glean. The original annotated, policy-abiding JSON is sent to PingCentre immediately after. After more validation and usage of Glean data has happened, we'll stop sending the data to PingCentre entirely.

Adding or changing telemetry

For now, do the same stuff we've always done in OMC: follow the process in the Activity Stream telemetry document with one exception: avoid adding any new nested objects, as these end up being flattened or stringified before being sent to glean. Note that when you need to add new metrics (i.e. JSON keys), they MUST to be added to browser/components/newtab/metrics.yaml in order to show up correctly in the Glean data.

Monitoring FxMS Telemetry Health

The OMC team owns an OpMon dashboard for the FxMS Desktop Glean telemetry with alerts. Note that it can only show one channel at any given time, here's a link to Windows Release. The dashboard is specified in firefox-messaging-system.toml, and reading the source can help clarify exactly what it means. We are the owner of this file, and are encouraged to adjust it to our needs, though it's probably a good idea to get review from someone in Data Science.

The current plan is to review the OpMon dashboard as a group in our weekly triage meeting, note anything that seems unusual to our Google docs log, and, if we want to investigate further, file a bug that blocks fxms-glean.

The dashboard is configured to alert in various cases, and those alerts can be seen at the bottom of the dashboard. As of this writing, the alerts have some noise to be cleaned up before we can automatically act on them.

Appendix: A Short Glean Primer, as it applies to this project (courtesy of Chris H-C)

• Glean is a data collection library by Mozilla for Mozilla. You define metrics like counts and timings and things, and package those into pings which are the payloads sent to our servers.
• You can see current FxMS Glean metrics and pings in the desktop section of the Glean Dictionary. The layer embedding Glean into Firefox Desktop is called Firefox on Glean (FOG).
• Documentation will be automatically generated and hosted on the Glean Dictionary, so write long rich-text Descriptions and augment them off-train with Glean Annotations.
• Schemas for ingestion are automatically generated. You can go from landing a new ping to querying the data being sent within two days.
• Make a mistake? No worries. Changes are quick and easy and are reflected in the received data within a day.
• Local debugging involves using Glean's ergonomic test APIs and/or the Glean Debug Ping Viewer which you can learn more about on about:glean.
• If you have any questions, the Glean Team is available across a lot of timezones on the #glean:mozilla.org channel on Matrix and Slack #data-help.